For our May HSC meeting we had a presentation from Greg Wiles from Wooster College who has been working with our Alaska Youth Stewards program for 5 years to core trees. He was presenting the results of the report attached below to this article. The results of their tree coring work (including living trees and ones buried by glaciers) give insight into climate and weather up to 3,800 years ago. It was a fascinating conversation and discussion on the science of tree rings and what you can learn from them!

In attendance : Gabe, Don Bolton, Greg Wiles, Jackson, Jeremy, Olivia, Archer, Jordan, Hayden, Jackie, Ian, Ben McCluckie, Susan, Travis, Lauryn, Baldonmarrow, Catherine Bolton

About Greg Wiles and Wooster

• Wooster is college in Ohio
• has worked in Ak for decades
• Wooster is an archive for tree aging
• Always looking for grant writing and partnership

What can we learn from the data?

• narrow rings are colder times
• summer is your fast growth
• our climate has century level change and decadal variation (Pacific Decadal Variation)
• cored modified trees – preserved the heritage of those trees through images and cores
• This is first time red cedar chronology has been done in AK
• may show that volcanic eruptions start cooling and then it persists due to ocean regulation.

Why do this work?

• SE Ak is very under-sampled for tree cores and aging
• What is the goal? What’s the long view?
• can gain a lot of information from buried trees that are emerging from melting glaciers
• have to do this quickly before they rot
• Glacier Bay has dozens of sampled logs
• can develop a chronology of ~ 3,800 years

What did they find?

• Alignment with other tree ring databases including “Miyake events” – 660 BC a big blow to our atmosphere seen throughout the world.
• Winter following winter  1698–1699. The ring index shows this for GBNP and corroborate the oral history
• on Ear Mountain can see the response of the glacier disappearing, they witnessed the glacier coming out and receding
• 1876 – most narrow ring, this was a super el niño year. brought famine to India

Understanding the Results

• The winter temperature is logged by tree ring index – this is an average representation of growth averaged across the whole tree ring database. When you are looking at graphs you can understand them this way :
  • above 1 it was a warmer winter
  • below 1 was a colder winter

What’s Next?

• looking to fund new work of sediment cores of lakes on pleasant island and Lemesurier Island

Questions and Answers

1. how small can the rings be? – can be too hard to count, can be measured in microns.
   1. How big can the rings get? multi millimeter or even a cm
2. Will trees live a shorter life span if they grow quicker in warmer climate? – answer – its possible
3. How much faster are trees growing?
   1. depends where you are. in upper tree line they are struggling vs at low elevation they are growing fast
4. How does Elevation and aspect play int the science? – took that into account, but also need to look at all possibilities and stressors.
5. In Kake there is site decline sites with trees over 800 years ago. Year 1200 there was cooling due to volcanic eruptions cooling due to sulfate in atmosphere
6. Why didn’t Kake yellow cedar see response in 1876?
   1. Yellow cedar may not respond to the same seasons

Link to Report for Download : AYS Tree Ring Report

AYS_report_draft